A typical electrostatographic printing process includes a development step whereby developing material, including toner or marking particles, is physically transported into the vicinity of a latent image, with the toner or marking particles being caused to migrate via electrical attraction to the image areas of the latent image so as to selectively adhere in an imaged configuration. Transfer of the developed image to a copy substrate typically occurs either by an electrostatic transfer technique or an adhesive transfer technique.
Adhesive transfer of the developed image to a copy substrate is advantageous for a broad range of substrates; however, it requires an application of high pressure and high temperature at the interface of the developed image and the copy substrate. In conventional electrophotographic systems, adhesive transfer is typically implemented after the developed image is transferred to an intermediate transfer member. Direct transfer from the imaging member, upon which the developed image is first formed, is typically not considered because the imaging member lacks the requisite compliance and the appropriate surface characteristics for successful adhesive transfer of the developed image directly to a copy substrate.
An example of a conventional approach may be found in U.S. Pat. No. 5,436,706, issued to Landa, wherein there is disclosed an intermediate transfer member which is in operative engagement with a photoconductive surface of a drum bearing the developed image. The intermediate transfer member is said to be operative for receiving the toner image from a photoconductive surface and for transferring the toner image to a final substrate. A heater to heat the intermediate transfer member may also be provided. Transfer of the image to the intermediate transfer member is said to be aided by providing an electric field between the intermediate transfer member and the image areas of the photoconductive surface. The intermediate transfer member is said to include a conducting layer underlying an elastomeric layer.
However, it is desirable that the developed image be directly transferable from an imaging member to a wide range of substrates. Direct, singlestep image transfer, that is, the transfer of the developed image from the imaging member upon which the developed image was first formed, incurs less of the image quality loss that is associated with conventional development and transfer techniques, such as those that employ an intermediate transfer member, additional bias, or an electrostatically-enabled transfer step.